Polymorphically expressed enzymes allelic variants

Human UGT1A genes contains multiple polymorphisms that alter enzyme structure (161) as well as a TATA-box promoter polymorphism, UGT1AT28, that leads to reduced constitutive expression in conditions such as Gilbert s syndrome (162,163) and to decreased conjugation of 2-hydroxyestradiol (164). However, there is no evidence that the variant UGT1AT28 allele affects induction of UGT1A1. 

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